- The desire to have more friends
Don't mean to sound rude but, humans are big social animals. Nonetheless, most people are having a hard time connecting with others in a social way. These feelings are in twofold, they either have not developed a good skills yet, or are just too afraid of getting hurt.
Regardless of the situation, some people get depressed when they're not having a good relationship as they intended to. This is why they go for pets, but pets are never enough. Humans are a perfect choice.
To some, having many friends will drive away their depression and sad feelings, while for others; it's vice versa. In an attempt to live a depression-free life, you'll need to erase this mentality from your head.